It is already known to use stereophotography in connection with producing dental articles and for dental work, in which case at least two cameras have generally been set up at a distance from one another and have been activated for taking pictures from different angles. It is also already known to use stereophotography in photogrammetric connections for measuring locations and positions of various surfaces, teeth, objects, etc. In order to be able to reach conclusions on the actual positions in space/the actual coordinate system, it is possible to use various aids, such as coordinate-measuring equipment, marked glass discs, etc.
There is a requirement facilitate the production of dental articles (dental bridges, e.g. dental caps, etc.) in a simpler way compared with present-day production methods. The invention is directed to solving this problem.
When producing dental bridges, prostheses and the like, a model is normally made at present by taking an impression with an impression compound in the mouth cavity. An object of the invention is to eliminate such modelling in the production of such dental articles.
The use of stereophotography is not entirely self-evident in this context, even if it does solve the problem of eliminating modelling with an impression compound. The use of two or more cameras for establishing stereophotographs presents problems, since it is difficult to prevent the patient from moving between two exposures. Even very small time delays between exposures and small movements of the patient, have a deleterious effect on the result. As a result, persons skilled in the art have heretofore concluded that the use of multiple cameras is not suited to everyday clinical use. The invention solves this problem and makes it possible for the present invention to be used in a practical application involving a patient.
Stereophotography must be able to provide a greater degree of accuracy or resolution in the dental product compared with previous uses of stereophotographic equipment. The invention solves this problem and also displays a greater degree of accuracy even in comparison with the use of the above mentioned modelling.
It has been shown that methods and arrangements used hitherto have led to static stress forces being built into the dental article/dental bridge in question. Even though these forces are relatively small, they lead in the long term to a collapse of all or part of the jaw bone in question. There is therefore a need for substantially greater accuracy of production than has previously been the case. The invention solves this problem too.
In connection with dental work in and around the mouth cavity, it is important that the photographic equipment employed have small dimensions and be easy to handle when in use. The space available in and around the patient's mouth cavity is limited, and the personnel providing the treatment should not need to possess any photographic expertise in order to perform their dental work. The invention solves this problem as well.
In accordance with the concept of the invention, the mirrors reflecting the optical radiation are used to form virtual lens functions which are arranged at a distance from one another to obtain a stereo imaging effect. In one embodiment, the interaction between the camera parts and the reflection surface(s) are locked in a mutual relationship at the site so that simplified use of the camera is achieved. The invention solves this problem too.
In a further embodiment, it is possible for the measurements in the images to be overdefined and for the positions of the lenses to be determined by means of solution of equation systems. This is also permitted by the invention.
There is a need to render more efficient all the operations surrounding the production of dental articles which are applied in the mouth cavity, with the whole production chain being taken into account, including examination of the patient's mouth and production in the actual material (titanium, for example) in the machine. The novel method and arrangement of the invention reveal new avenues for realizing such methods and arrangements and can be used, in connection with methods and the arrangements known in the art.
When working in the mouth cavity, it should be possible, for example, to effect imaging of a number of implants (2 to 6 implants, for example) in a jaw bone both at the level of the fixture and at the level of the spacer. The invention solves this problem.